Inquiries on Controlled Environment systems


#1

Hello OpenAg community!
My name is Kshaunish Soni, I am a senior in high school and a builder on the Digital Food Lab. We have built a prototype of a fully automated and regulated farm. We used the MIT OpenAg, Food Computer, and Foam Farm as inspiration to build. We seemed to have some trouble with the Controlled Environment systems, specifically heating and cooling. How did the Food Computer and its team manage to create a fully controlled environment maintaining approximately 55-65 degrees Fahrenheit in a climate that ranges from -10 to 100 degrees F (Cambridge, MA)? We decided to use Peltier coolers to absorb heat and keep the growing chamber cool, while heating a humidifying the chamber when needed. All of this is done through autonomous code programmed on an Arduino, all available on Github under our name “Digital Food Lab”. Any help would be greatly appreciated. Thank you and have a nice day!


What EC and temperature sensor and ph sensor shall we buy?
#2

I found the Digital Food Lab on Github but your README appears to be empty. Is there any documentation I can reference?

I’m a little confused as to what you’re looking for help with. The V2 PFC uses a chiller which is currently commercially unavailable, but that is what maintains the temperature. I think they chose not to use a humidifier because they didn’t find it necessary to ever raise the temperature.

Please post some pictures of your project as well as more information about the heating/cooling portion and what you’re looking for help with. It sounds like you have something figured out with the peltier, perhaps look at this previous thread as well, I don’t think the project was finished but it may help answer some ?s you’ve had.

Also, I know @sameersd has similar questions regarding the chiller. @adrianlu @TechBrainstorm is the chiller something you’ve given any thought to? I’ve toyed around with trying to create a water chiller out of a USB minifridge, I think that if we can cool the water to about 65-70 degrees not only will it help increase the DO of the water but cool the entire chamber. What I’m getting at is that regulating the water temp may be a more efficient method of regulating the entire temperature of the PFC. I’ve seen this done with aquaponics, and hear it’s relatively common for hydroponic CEA greenhouses.

Here is proof of that from Cornell’s 10-year study of hydroponic lettuce production.

“Thompson et al. (1998) reported on shoot and root temperature effects on lettuce growth in deep flow hydroponics. It was found possible to produce a quality lettuce crop even when grown at continuously elevated greenhouse aerial temperatures (above 24°C during the light period) but only if the root zone temperature (nutrient solution) was kept below 20°C. This result showed that successful lettuce production is possible in warmer climates when the temperature of the root zone environment is maintained at appropriate levels.


#3

I have a couple of other questions:

Why are you using AM2315 & DHT11? Why not one or the other?

What is your water depth sensor?

Do you have PH balancing and EC dosing set up in terms of hardware calibration? Are you using peristaltic pumps or something else?

Please post pics, it will help all of us give you better feedback!


#4

@Webb.Peter,

So far @spartan081 has prototyped a air-cooling method via a misting spray and fan. We’re going to see if and how the relative humidity change affects the grow chamber.


#5

Very interested to hear these results! I’ve considered something similar but been worried about the humidity - these swamp coolers tend to only be effective in low humidity environments (St. Louis is crazy humid).

I will say that when I inquired as to why the V2 has no humidifier, it was because they found they were generally above the desired setpoint anyway (plants transpire lots of water).

Lately, I’m leaning more towards just controlling the water temperature, and not worrying about air temp so much. Was this a problem with the V1 (we added an external water cooler on ours)? From what I’ve read plants can generally survive much higher air temps than they can water temp. Check out the conversations being had here: Recommendations for Water Chiller?